Battery grid lead scrap melting apparatus and method

ABSTRACT

An apparatus and process for melting and using scrap pieces of lead or lead alloy from making a web of connected grids for a lead acid battery by forming holes through a solid strip of lead or lead alloy. The scrap pieces may be compacted into briquettes which are submerged in a pool of liquid lead or lead alloy below the top surface of the pool and melt in the pool. Liquid lead from the pool may be cast into solid strips from which webs of grids are made.

TECHNICAL FIELD

The present invention relates generally to the melting and use of leadscrap and more particularly to the melting and use of lead scrap in themanufacture of grids for lead acid batteries.

BACKGROUND

The grids of a lead acid battery are made of a lead or a lead alloy(hereinafter referred to as lead) and the commercial manufacture of leadgrids, particularly for positive electrodes, produces a significantamount of solid lead scrap in the form of small pieces of lead frompunching, slitting, and trimming operations which must be re-melted forreuse in making lead grids.

Grids for lead acid batteries may each have a plurality of spaced apartwire segments interconnected at nodes and a plurality of open spacesbetween the wire segments. The manufacture of a web of a plurality ofserially connected lead grids by punching holes through a cast or castand rolled solid strip of lead typically produces 80% or more by weightof scrap from the solid lead strips. Thus, to economically form leadgrids, it is necessary to re-melt and use this scrap in forming longstrips of solid lead. While these punched pieces of scrap vary ingeometry, they most generally have a thickness in the range of about0.020 to 0.045 of an inch and a width and length typically each of whichdoes not exceed about 0.6 of an inch. Punched scrap or slugs often aregenerally rectangular in shape but may be square, trapezoidal,triangular, etc.

When casting solid lead strip the scrap typically is returned to afurnace which already has a pool of liquid lead therein. The scrappieces tend to float on the surface of the liquid lead where they arequickly oxidized with a significant portion by weight becoming dross andalso may have their alloy content significantly reduced. A portion ofthe scrap may also sink into the liquid lead to the bottom of thefurnace where it often piles up into a glob or mass of small leadparticles that require excessively high furnace temperatures to melt andliquefy them which also creates increased oxidation, dross, and shorterequipment life. Significant oxidation and dross produces lead scrap thatcannot be reused and thus must be removed, typically manually, from thesurface of the pool of lead in the furnace and smelted in a separatefurnace usually with alloys being added before it can be re-used to casta solid lead strip. Significant oxidation and dross of lead alloy scrapdramatically changes and reduces its alloy content. Excessive dross alsosignificantly increases lead dust and vapor fumes in the air which mayhave a negative effect on human health and the environment.

SUMMARY

In at least some implementations, a process of liquefying a plurality ofpieces of solid scrap lead may include providing a pool of liquid leadhaving a surface, compacting a plurality of pieces of lead scrap into abriquette, and submerging the briquette in the pool of liquid lead andcompletely below the surface of the pool of liquid lead. In at leastsome implementations the pool of liquid lead may have a temperature ofat least 650° F. and desirably in the range of 750° F. to 950° F. Thebriquettes may have a density of at least 10.3 g/cc³, desirably at least10.6 g/cc³ and preferably about 11.0 g/cc³ and a weight of at least 1kg, desirably 1-2 kg and preferably 8-25 kg.

In at least some implementations, the process may include casting asolid lead strip from a pool of liquid lead, punching the solid leadstrip to form a web of serially connected battery grids and a pluralityof pieces of scrap lead punched from the solid strips, compacting aplurality of the pieces of scrap lead into briquettes and submerging thebriquettes in the pool of liquid lead to melt the briquettes. The poolof liquid lead may be maintained at a temperature of at least 650° F.and desirably in the range of 750° F. to 950° F. The briquettes may beformed with a density of at least 10.3 g/cc³ desirably at least 10.6g/cc³ and preferably 11.0 g/cc³ when at room temperature and may have aweight of at least 1 kg, desirably 2 kg and preferably 8 kg to 25 kg.

In at least some implementations the solid lead strip may be formed by acontinuous casting machine, the web of lead grids and scrap lead piecesmay be made by a progressive die punching the solid lead strip, the leadscrap pieces may be formed into briquettes by a compacting press and thebriquettes submerged in a pool of liquid lead being supplied to thecasting machine forming solid lead strips. In some implementations, thethickness of the solid lead strip may be decreased and its longitudinallength increased by passing it through rolling mills before forming theweb of lead grids.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of certain embodiments and best modewill be set forth with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a suitable industrial manufacturing linefor casting a solid strip of lead, punching it to produce a web of gridsfor lead acid batteries and to re-melt and use scrap produced bymanufacture of webs of multiple grids;

FIG. 2 is an schematic view of a melting furnace, strip caster, trimmer,and reeler of the manufacturing line of FIG. 1;

FIG. 3 is a plan view of one grid of a web of connected grids producedby a progressive punching die set of the manufacturing line of FIG. 1;

FIG. 4 is a fragmentary sectional view taken generally on line 4-4 ofFIG. 3;

FIG. 5 is a fragmentary sectional view taken generally on line 5-5 ofFIG. 3;

FIG. 6 is a semi-schematic view of lead scrap;

FIG. 7 is a perspective view of a mass of lead scrap compacted into oneform of a briquette;

FIG. 8 is a view of a mass of lead scrap compacted into another form ofa briquette;

FIG. 9 is a perspective view of a scrap compacting press of the lineFIG. 1;

FIG. 10 is a semi-schematic sectional view of a portion of thecompacting press of FIG. 9;

FIG. 11 is a semi-schematic fragmentary sectional view of the presstaken generally on line 11-11 of FIG. 10;

FIG. 12 is a perspective view of a die block of the press of FIG. 9;

FIG. 13 is a semi-schematic schematic perspective view of the compactingpress and a melting furnace of the line of FIG. 1.

DETAILED DESCRIPTION

A process of making a web of serially connected battery grids mayinclude forming holes through a solid strip of lead which produces leadscrap pieces such as slugs from die punching operations. Pieces of thelead scrap may be compacted into briquettes which will readily submergein a pool of liquid lead completely below the surface of the pool.Liquid lead from the pool may be used to cast a solid strip of lead fromwhich the web of grids may be made. The briquettes of scrap may have adensity of at least 10.3, desirably 10.6, and preferably 11.0 grams percubic centimeter [g/cc³] and a weight of at least 1 kilogram (kg),desirably 2 kg and preferably 8 kg to 25 kg. In mass production ofbattery grids the briquettes may be added to the pool of liquid lead ata rate of at least 1,900 kg, desirably 2,300 kg and preferably 3,000 kgto 4,800 kg per hour. The pool of liquid lead may be at a temperature ofat least 650° F. and desirably in the range of 750° F. to 950° F. Thesolid strip may be cast by a continuous caster at a rate of 2,300 kg perhour and desirably 3,900 kg to 6,300 kg per hour. For automotive leadacid batteries the solid strip may be reduced to a thickness in therange of about 0.020 to 0.045 of an inch [0.50 to 1.15 centimeters (cm)]and the webs of grids formed at a rate of about 80 to 150 linear feetper minute (24 to 46 lineal meters per minute).

Referring in more detail to the drawings, FIG. 1 illustrates a suitableproduction line 20 which may implement this process by castinglongitudinally elongate solid strips of lead and producinglongitudinally elongate webs each with a plurality of lead acid batterygrids connected in series, and by recovering, re-melting and using scrappieces of lead produced by trimming and/or punching operations in makinga web of a series of connected grids from a solid strip of lead. Thisproduction line may include a lead solid strip casting line 22, a gridforming line 24, a scrap compacting line 26, and one or more furnaces 28which melt lead and supply liquid lead to the casting line 22.

The casting line 22 may have a casting machine 30 which in use casts alongitudinally elongate continuous strip 32 of solidified solid lead.This strip is typically passed through a series of rolling mills 34which successively reduce the thickness and increase the longitudinalextent or length of the cast strip. In each rolling mill 34, the stripmay pass through the nip of a pair of co-rotating rollers to reduce thethickness of the strip. The strip 32′ emerging from the downstreamrolling mill 34 may pass through an edge trim cutter and/or slitter 36and may be wound into a coil or coils by a reeler machine 38 forsubsequent further processing. If the trim cutter or slitter 36 produceslong pieces of scrap they may be broken into smaller pieces of scrap bya chipper 40. Typically, the caster may produce a lead solid strip 32with a thickness in the range of 0.18 to 0.5 of an inch (4.5 to 13.0 mm)and a width in the range of 4 to 14 inches (100 to 360 mm) at a rate inthe range of 3 to 20 lineal feet (1 to 6 meters) per minute. Typicallythe rolling mills 34 collectively may reduce the nominal thickness ofthe cast strip 32 to an elongate strip 32′ of about 0.020 to 0.045 of aninch (0.5 to 1.15 mm) thick. A suitable lead solid strip casting line isdisclosed in United States Published Application US-2018-0342770-A1 ofthe present Applicant, Wirtz Manufacturing Company of Port Huron, Mich.,U.S.A., the disclosure of which is incorporated herein by reference inits entirety and thus the casting line will not be described in furtherdetail herein.

The grid forming line 24 may include a reeler 42 which unwinds coils ofsolid lead strips 32′ which may advance through a welder 44, to a loopfeeder 46 which supplies the solid strip to a press 48 with aprogressive die set 50 which punches holes through the lead strip toform a web 52 of a series of connected lead grids 54. The welder 44 maybutt weld together the adjacent ends of individual solid lead strips toprovide a substantially continuous longitudinally elongate strip 32′ fedto the progressive die set. The web 52 of lead grids 54 may pass throughan ultrasonic cleaner 56 and be wound into coils by a reeler 58 forfurther processing of the webs 52 of connected grids.

As shown in FIG. 3 the progressive die set 50 may form each grid 54 ofthe web 52 with a plurality of generally horizontally or longitudinallyextending wire segments 60 and a plurality of generally verticallyextending wire segments 62 intersecting and joined with the horizontalwire segments at nodes 64. Each grid perimeter may also include a frame66 of generally horizontally extending segments 68 and generallyvertically extending segments 70. The frame and wire segments may beformed by punching out portions of the solid strip to form throughopenings, holes or spaces 72 between the wire segments. The punching diewill initially form the wire segments with a generally rectangularcross-section which if desired may be stamped or coined by a suitabledie 74 as shown in FIGS. 4 and 5 to form angled lands 76 on the wiresegments which are inclined to the generally planar and parallel outerfaces 78, 80 of each grid. These angled lands 76 may be formed by eithera portion of the progressive die set 50 or by a separate stamping orcoining die set and press downstream of the progressive die set 50. Toincrease the adhesion of subsequently applied and cured battery paste tothe grid wires, some or all of their exterior surfaces may be formedwith a controlled surface roughness 82 which may be produced by stampingor coining operations. A suitable method, apparatus and line forpunching a lead solid strip to produce a web of grids is disclosed inU.S. Pat. No. 8,875,361 of Applicant the disclosure of which isincorporated herein by reference in its entirety and thus this gridforming line 24 will not be described in further detail herein.

The punching of the lead solid strip 32′ to form the grids 54 producessignificant quantities of scrap lead pieces 84 (FIG. 6) which may beadvanced by a conveyor 86 to a compacting press 88 which formsbriquettes of the scrap which are returned to the furnace 28. Typically,the grid forming press 48 and progressive punching die set 50 willproduce about 125 to 175 lineal feet (40 to 55 lineal meters) per minuteof a web 52 of connected grids 54 with a thickness of about 0.020 to0.045 of an inch (0.5 to 1.15 mm) and a transverse web width of about 4to 14 inches (100 to 360 mm) and typically produce four or more tons(3,100 kg) per hour of scrap lead pieces 84 which is usually at least65% and typically about 80% to 85% by weight of the solid lead strip32′. Scrap 84 from the trimmer 36 and chipper 40 may also be advanced bya conveyor 90 to the conveyor 86 and thus to the compacting press 88.

In the compacting line 26 a plurality of pieces of scrap 84 may becompacted into a block or briquette having sufficient integrity that itwill not readily separate into small pieces and of sufficient density sothat when dropped onto the top surface of a pool of liquid lead in afurnace it will readily sink below the surface of the pool of liquidlead and toward the bottom of the pool of lead. It is believed that theability of a briquette of scrap lead pieces to submerge below thesurface of a pool of liquid lead and toward the bottom of a pool ofliquid lead is primarily a function of the buoyancy of the liquid leadacting on the briquette. Unless dropped or propelled from above the topsurface of the pool of liquid lead in theory and in accordance withArchimedes' principle the briquette must have sufficient density (weightper unit of volume) at least substantially equal to the buoyancy of theliquid lead in the furnace which for liquid lead at a temperature ofabout 650° F. to 750° F. is about 10.58 g/cm³ and at a temperature of950° F. is about 10.43 g/cm³.

It is believed that lead scrap compacted into a briquette weighing atleast about 1 kg and having a density of at least about 10.6 g/cm³ whendropped from at least 0.5 feet (0.15 meter) above the top surface of apool of liquid lead at a temperature of 750° F. substantially verticallyinto such pool will readily and rapidly sink below the top surface ofsuch pool (assuming the same gravitational force on both the briquetteand the pool of liquid lead) and be melted therein. Some empiricaltesting and resulting data indicates that a briquette in the form of acylinder 90 (FIG. 7) of lead scrap having a density of 11.0 g/cm³ and aweight within a range of 5 to 10 lbs. (2 to 4 kg) when dropped from 0.5feet (0.15 meter) above and substantially vertically into a pool ofliquid lead at 750° F. readily and rapidly is submerged completely belowthe surface of the pool of liquid lead and melted therein withoutproducing any significant dross and without a loss of Calcium and tinalloys in a lead calcium tin alloy typically used in making lead acidbattery grids. A briquette of scrap lead pieces in the form of a block,hexahedron, or parallelepiped 92 (FIG. 8) having a density of about 11.1g/cc³ and a weight of about 30 pounds (12.6 kg) when dropped from 0.5feet (0.15 meter) above the surface of and substantially vertically intoa pool of liquid lead at 750° F. readily and rapidly submergescompletely below the surface of the pool of liquid lead and is meltedtherein without producing any significant dross and without loss of itscalcium, tin, and calcium tin alloys. These briquettes 90, 92 of scraplead pieces may be added to a pool of 16,000 to 60,000 pounds (3,200 to23,600 kg) of liquid lead nominally at 750° F. at the rate of about8,000 lbs. (3,100 kg) per hour when and as liquid lead is supplied tothe caster of solid strips at the rate of about 12,000 lbs. (4,800 kg)per hour along with additional solid lead being added to and melted inthe pool of liquid lead at the rate of about 2,000 to 4,000 lbs. (780 to1,560 kg) per hour. Typically, the added lead is in the form of socalled “pigs” of 60 to 100 lbs. (25 to 40 kg) each or “hogs” of 500 to2,000 lbs. (200-800 kg) each of solid lead at room temperature. It maybe desirable to use briquettes of at least 5 pounds and preferably 20 to60 pounds (8 to 25 kg) and a density of at least 10.6 and desirably 10.8g/cc³ supplied to the pool of liquid lead at a rate of at least 5,000(1,900 kg) and as much as 8,000 to 12,000 pounds (3,100 to 4,800 kg) perhour depending on the capacity of the caster of the lead solid strip.

A suitable press 88 for compacting scrap lead pieces into briquettes issemi-schematically illustrated in FIGS. 9-13. This press compacts scrappieces 84 in two stages to form a briquette. The compacting press mayhave a hopper 94 in which scrap pieces 84 are received and moved byrotating augers 96 toward an intermittently rotating auger 98 whichintermittently feeds scrap pieces into an elongate chamber or cavity 100in which a pressing plate 102 (FIG. 11) is movable between retracted andextended positions by a hydraulic ram 104 which in operation is actuatedby pressurized hydraulic oil supplied by a hydraulic pump 106 driven byan electric motor 108. As shown in FIGS. 10 and 11 in the first stagethe ram 104 extends the plate 102 to partially compact a quantity orbatch of scrap pieces 84 in the cavity 100. In the second stage, thispartially compacted scrap is transferred into one of two transverselyspaced apart die cavities 110, 110′ through a reciprocative die plate112 (FIG. 12) and further compacted therein to form a briquette by aplunger 114 with a complimentary cross-section being advanced throughthe chamber 100 and into one of the die cavities 110 or 110′ by ahydraulic ram 116. The distal end of this die cavity is closed orcovered by an adjacent planar face of a plate 118. The die plate 112 ismoved back and forth by a hydraulic ram 120 to alternately align one andthen the other of the die cavities 110, 110′ with the plunger 114.

This briquette is removed from its associated die cavity 110 or 110′ andtransferred to one of two outlet troughs 122 or 122′ by retraction ofthe plunger 114, lateral movement of the die plate 112 by the hydraulicram 120 to align the cavity 110 or 110′ with the formed briquettetherein with one of the two spaced apart exit holes 124, 124′ throughthe plate 118, and thereafter advancement of associated ejector pins126, 126′ by the hydraulic ram 116 which also simultaneously againadvances the plunger 114 through the cavity 100 and into the other emptydie cavity 110′ or 110 to form another briquette therein. The die plate112 also has a clearance through hole 127′ for the ejector pin 126′.Each time the plunger 114 is retracted from one of the cavities 110 or110′ the die plate is advanced or retracted by the hydraulic ram 120 toalign the other cavity 110′ or 100 with the plunger. The ram 104 andauger 98 are cycled to recharge the cavity 100 with a new batch of scrappieces and partially or pre compact them therein for transfer andfurther compaction in the empty one of the two die cavities 110, 110′.Thus, in operation the press 88 alternately compacts a briquette in onedie cavity 110 or 110′, while transferring a formed briquette out of theother die cavity 110′ or 110 and onto one of the two troughs 122, 122′.Thus, formed briquettes are alternately transferred to one and then theother of the two troughs.

As shown in FIG. 13, once a trough is full of abuting briquettes, eachtransfer of another briquette into the trough also advances alldownstream briquettes and typically discharges a briquette from theother end of the trough either onto a conveyor 128 (FIG. 1) whichdelivers the briquettes to the furnace 28 or directly into the furnace28 (FIG. 13). The briquettes produced by this press may be generallycylindrical 90 as shown in FIG. 7 or desirably rectilinear 92 as shownin FIG. 8. The compacted briquettes may be in the form of a cylinder,square, hexahedron, parallelpiped, or of another shape as will apparentto one skilled in the art. A suitable compacting press is available fromRUF US, Inc., 771 Sugar Lane, Elyria, Ohio, USA 44035 as model No. RUF1100.

As shown in FIG. 13 the furnace 28 may typically have a container or pot130 with an open top 132, and in which lead is melted by heat producedtypically by natural gas fired burners underlying and in some casespartially surrounding portions of the pot. Melted liquid lead from thefurnace may be delivered by a molten lead pump assembly 134 to the stripcaster 30 desirably without exposing the liquid lead to the atmosphereto at least substantially preclude migration of lead impurities anddross to the caster. The pump assembly 134 may have a centrifugal pump136 with an inlet 138 submergible in the pool of liquid lead in the pot130 of the furnace or in a holding well (not shown) of liquid leadtransferred from the furnace. The pump may be driven by an electricmotor 140 through a shaft connected to an impeller. Desirably the pumpinlet 138 is positioned in the range of about ¼ to ¾ of the verticalheight or extent of the pool of liquid lead in the furnace or holdingwell. Typically, the pump assembly 134 may deliver excess liquid lead tothe casting machine 30 through a pipe or conduit 140 with the portionnot used by the casting machine being returned to the furnace or holdingwell through a pipe or conduit 142 below the surface of the pool ofmolten lead in the melting furnace or holding well. If needed, theconduit 140 for delivering lead to the casting machine and the conduit142 for returning excess liquid lead from the casting machine 30 may bethermally insulated and if needed equipped with heaters such as electricheaters to ensure that in use the lead remains in a liquid state and ata desirable temperature as it flows through the conduits to and from thecasting machine. Typically, the pump assembly may deliver liquid lead tothe casting machine at a pressure in the range of 30 to 40 psi gauge(207 to 276 kPa gauge) and a flow rate of 400 to 600 lbs. (181 to 272kg) of liquid lead per minute. A suitable liquid lead transfer pumpassembly is commercially available from the Applicant hereof, WirtzManufacturing Company of Port Huron, Mich., USA. A suitable pumpassembly is also believed to be disclosed in U.S. Pat. No. 7,507,367 thedisclosure of which is incorporated herein by reference in its entirety.

The forms of the invention herein disclosed constitute presentlypreferred embodiments and many other forms and embodiments are possible.It is not intended herein to mention all the possible equivalent formsor ramifications of the invention. It is understood that the terms usedherein are merely descriptive, rather than limiting, and that variouschanges may be made without departing from the spirit or scope of theinvention.

1. A production line for liquefying a plurality of pieces of scrap oflead or a lead alloy comprising; a furnace for heating a lead or a leadalloy to provide a pool of liquid lead or lead alloy with the poolhaving a surface; a compacting press for compacting a plurality ofpieces of scrap of lead or lead alloy into briquettes; and a device fordelivering the briquettes to the pool of liquid lead or lead alloy;whereby the briquettes are submerged in the pool and completely belowthe surface of the pool.
 2. The line of claim 1, wherein the compactingpress is constructed and arranged to produce briquettes having a densityof at least 10.3 g/cm³ and a weight of at least 2 kg.
 3. The line ofclaim 2, also comprising a caster constructed and arranged to cast asolid strip of lead or lead alloy, and wherein the furnace isconstructed and arranged to maintain the pool of lead or lead alloy at atemperature of at least 650° F., the compacting press is constructed andarranged to produce at least 1,900 kg per hour of briquettes, thefurnace is constructed and arranged to receive at least 1,900 kg perhour of briquettes, to melt the briquettes, to maintain the pool of leador lead alloy at a temperature of at least 650° F. and to supply atleast 2,300 kg per hour of liquid lead to the caster of the solid stripof lead or lead alloy.
 4. The line of claim 2, which also comprises apunching press constructed and arranged to punch lead or a lead alloyfrom the solid strip to produce a web of a series of connected batterygrids and pieces of scrap at the rate of at least 1,900 kg per hour ofscrap, and a conveying device constructed and arranged to receive scrapfrom the punching press and to deliver scrap to the compacting press atthe rate of at least 1,900 kg per hour.
 5. The line of claim 3, whereinthe compacting press is constructed and arranged to produce briquetteshaving a density of at least 10.6 g/cm³ and a weight in the range of 2to 25 kg.
 6. The line of claim 4, wherein the compacting press isconstructed and arranged to produce briquettes having a density of atleast 10.6 g/cm³ and a weight in the range of 2 to 25 kg.
 7. A processof liquefying a plurality of pieces of scrap of lead or a lead alloycomprising: providing a pool of liquid lead or lead alloy having asurface; compacting a plurality of pieces of scrap of lead or lead alloyinto a briquette; and submerging the briquette in the pool of liquidlead or lead alloy and completely below the surface of the pool.
 8. Theprocess of claim 7, comprising compacting the briquette to a density ofat least 10.3 g/cm³.
 9. The process of claim 7, comprising compacting asufficient quantity of scrap to form a briquette having a weight of atleast 1 kg.
 10. The process of claim 8, comprising compacting asufficient quantity of scrap to form a briquette having a weight in therange of 2 kg to 25 kg.
 11. The process of claim 7, comprising heatingthe pool of liquid lead or lead alloy to a temperature of at least 650°F.
 12. The process of claim 7, comprising compacting a plurality ofbriquettes having a density of at least 10.6 g/cm³ and submerging thebriquettes in the pool of lead or lead alloy and completely below thesurface of the pool.
 13. The process of claim 7, comprising compacting aquantity of scrap into a briquette having a density of at least 10.6g/cm³ and a weight in the range of 2 kg to 25 kg.
 14. The process ofclaim 7, comprising compacting a quantity of scrap to form a briquettehaving a density of at least 10.3 g/cm³ and sufficient to withstand adrop vertically of 2 meters onto a flat surface of concrete having anominal thickness of at least 0.1 meter without breaking the briquette.15. The process of claim 7, comprising compacting a plurality ofbriquettes having a density of at least 10.6 g/cm³ and a weight of atleast 2 kg and submerging the briquettes in the pool of liquid lead orlead alloy at the rate of at least 1,900 kg of briquettes per hour. 16.The process of claim 7, comprising dropping the briquette into the poolthrough the surface of the pool.
 17. The process of claim 7, which alsocomprises casting from at least some of the liquid lead or lead alloyfrom the pool a longitudinally elongate solid strip of lead or leadalloy of a predetermined thickness, reducing the thickness of the solidstrip, punching holes through the solid strip to form a web of aplurality of serially connected battery grids and produce a plurality ofpieces of scrap punched from the solid strip, compacting a plurality ofthe pieces of scrap into a plurality of the briquettes, and submergingthe briquettes in the pool of liquid lead or lead alloy and completelybelow the surface of the pool.
 18. A process of making a web ofconnected battery grids with lead or a lead alloy comprising: providinga pool of liquid lead or a lead alloy having a surface; casting liquidlead or lead alloy from the pool into a longitudinally elongate solidstrip of the lead or lead alloy with a predetermined thickness; reducingthe thickness of the solid strip; punching the solid strip to form a webof serially connected battery grids and a plurality of pieces of scrapof the lead or lead alloy punched from the solid strip; compacting aplurality of the pieces of scrap of the lead or lead alloy intobriquettes having a density of at least 10.3 g/cc³; and submerging thebriquettes in the pool of liquid lead or lead alloy and completely belowthe surface of the pool to thereby melt the briquettes into liquid leador lead alloy in the pool.
 19. The process of claim 18, comprisingcompacting briquettes having a weight of at least 2 kg at a rate of atleast 1,900 kg per hour of briquettes and submerging the briquettes inthe pool of liquid lead or lead alloy at the rate of at least 1,900 kgper hour of briquettes.
 20. The process of claim 19, comprising heatingthe pool of liquid lead or lead alloy to a temperature to at least 650°F.
 21. The process of claim 19, comprising compacting a sufficientquantity of the plurality of pieces of scrap into briquettes having aweight in the range of 2 kg to 25 kg.